1. Field of the Invention
The present invention relates to a weighing apparatus. In particular, the present invention related to a portable weighing apparatus for weighing items, such as gas bottles or the like.
2. Description of the Related Art
Gas bottles are used for a large variety of applications in domestic, commercial and industrial settings. Regardless of the application in which bottled gas is being used, it is advantageous to know the amount of gas remaining in a gas bottle so that a user does not, in the middle of an activity, have to change gas bottles or, worse, run out of gas completely.
The most simple method of measuring the amount of gas remaining in a gas bottle is to shake the bottle and estimate the quantity remaining. However, this technique is often extremely inaccurate.
Some attempts have been made to develop devices that measure, with greater accuracy, the quantity of gas in a gas bottle. These devices include a plastic strip adhered to the outer surface of a gas bottle. The level of the gas in the bottle may be determined by pouring boiling water over the strip, causing the strip to change colour.
It is possible to determine the quantity of gas in a gas bottle by weighing the bottle on a set of scales. However, for this technique to work with any accuracy it is necessary to know the weight of the bottle when empty (the tare weight normally marked on the bottle) and then subtract this from the combined weight of the bottle and gas, making this technique slow and cumbersome.
A more sophisticated solution to this problem was disclosed in Australian Innovation Patent No. 2004100314. In this patent, a device was disclosed that could be set to automatically deduct the tare weight of the bottle from the combined weight of the gas and the bottle when a gas bottle was attached to it. However, this device operates as a set of scales, meaning that the weight must be read directly from the scale before the gas bottle is removed, or else the measurement will be lost.
Thus, there would be an advantage if it were possible to provide a weighing apparatus that could measure the quantity of gas in a gas bottle and at least temporarily retain that measurement even when the gas bottle has been removed from the weighing apparatus.
It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.
Throughout this specification, the term “comprising” and its grammatical equivalents shall be taken to have an inclusive meaning unless the context of use indicates otherwise.